We are studying the chromatin structure in which the oocyte-type 5S RNA genes of Xenopus are involved. Our experiments are designed to determine whether this 5S chromatin has the common, repeating nucleosome structure, whether the location of nucleosomes is determined by the DNA sequence, and what influence transcriptional activity has on this chromatin structure. In addition, we are investigating the recombination potential of 5S DNA in bacteria. We are selecting recombinants between two different bacterial plasmids, each of which carries a segment of 5S DNA and examining the fate of the short repeated sequences in the A+T-rich spacer. These experiments are designed to test the notion that these subrepeats are shuffled by unequal crossing-over in a process which accounts for the evolutionary maintenance of repeated gene families. BIBLIOGRAPHIC REFERENCE: A.J. MacGillivray, D. Rickwood, A. Cameron, D. Carroll, C.J. Ingles, R. Krauze and J. Paul, "Methods for Isolation and Characterization of Chromosomal Non-histone Proteins," Methods in Enzymology, v. 40, p. 160 (1975).